Rapid prototyping is the fast fabrication of a physical part, model, or assembly using 3D computer-aided design (CAD). This process is typically accomplished through additive manufacturing, commonly known as 3D printing.
When the design closely matches the proposed finished product, it is referred to as a high-fidelity prototype. Conversely, a low-fidelity prototype has significant differences compared to the final product.
Rapid prototyping (RP) encompasses a variety of manufacturing technologies, with most processes utilizing layered additive manufacturing. However, other technologies such as high-speed machining, casting, molding, and extruding are also employed for RP.
While additive manufacturing is the most common method for rapid prototyping, more conventional processes can also be used to create prototypes. These processes include:
1. Subtractive Manufacturing: This method involves carving a block of material to produce the desired shape using techniques such as milling, grinding, or turning.
2. Compressive Manufacturing: In this process, a semi-solid or liquid material is forced into the desired shape and then solidified. Examples include casting, compressive sintering, and molding.
This fast and affordable technique was the first successful method of commercial 3D printing. It uses a bath of photosensitive liquid, which is solidified layer by layer using a computer-controlled ultraviolet (UV) light.
Used for both metal and plastic prototyping, SLS employs a powder bed to build a prototype one layer at a time, using a laser to heat and sinter the powdered material. However, the strength of the parts is generally not as high as with SLA, and the surface of the finished product is usually rough, often requiring secondary finishing work.
This inexpensive and easy-to-use process is common in most non-industrial desktop 3D printers. It utilizes a spool of thermoplastic filament, which is melted inside a printing nozzle barrel. The liquid plastic is then laid down layer by layer according to a computer deposition program. While early results often had poor resolution and strength, the process is rapidly improving, making it a fast and cheap option ideal for product development.
Often referred to as powder bed fusion, this process is favored for creating high-strength, complex parts. Selective Laser Melting is frequently used in the aerospace, automotive, defense, and medical industries. This powder bed-based fusion process utilizes fine metal powder, which is melted layer by layer to build either prototype or production parts using a high-powered laser or electron beam. Common SLM materials used in rapid prototyping include titanium, aluminum, stainless steel, and cobalt chrome alloys.
This inexpensive process is less sophisticated than SLM or SLS, but it does not require specially controlled conditions. LOM builds up a series of thin laminates that are accurately cut with laser beams or another cutting device to create the CAD pattern design. Each layer is delivered and bonded on top of the previous one until the part is complete.
Similar to SLA, this technique uses the polymerization of resins cured by a conventional light source. While faster and cheaper than SLA, DLP often requires support structures and post-build curing. An alternative version is Continuous Liquid Interface Production (CLIP), where the part is continuously pulled from a vat without the use of layers. As the part is pulled, it crosses a light barrier that alters its configuration to create the desired cross-sectional pattern on the plastic.
This technique allows for one or many parts to be printed simultaneously, though the parts produced are not as strong as those created using SLS. Binder Jetting uses a powder bed onto which nozzles spray micro-fine droplets of a liquid binder to bond the powder particles together, forming a layer of the part. Each layer may be compacted by a roller before the next layer of powder is laid down, and the process begins again. When complete, the part may be cured in an oven to burn off the binding agent and fuse the powder into a coherent part.
Product designers use rapid prototyping for the quick manufacturing of representative prototype parts. This aids in visualization, design, and the development of the manufacturing process ahead of mass production.
Originally, rapid prototyping was used to create parts and scale models for the automotive industry. However, it has since expanded to a wide range of applications across multiple industries, such as medical and aerospace.
Another application of rapid prototyping is rapid tooling. In this process, a part, such as an injection mold plug or an ultrasound sensor wedge, is created and used as a tool in another manufacturing process.
